The invention relates generally to asphalt and soil compacting work machines, and more particularly to a split drum design for such work machines.
Compacting work machines are commonly employed for compacting freshly laid asphalt, soil, and other compactable materials or substrates. For example these work machines may include plate type compactors or rolling drum compactors with one or more drums. The drum type work machines function to compact the material over which the machine is driven. In order to more efficiently compact the material the drum assembly often includes a vibratory mechanism for inducing vibratory forces on the material being compacted.
It is common practice in the compacting of asphalt to use work machines that include two rotating drums to more efficiently compact the material. Double drum compactors are used so that during each pass over the material being compacted each drum performs a portion of the compacting process. These double drum compactors either have an articulating frame or each drum has the ability to pivot about a vertical axis so that the work machine can be steered in a desired direction during operation. During tight turning operations the outside of the drum can slide over the material being compacted and causes a tear in the material because the outside portion of the drum desires to rotate faster than the inside portion. On the other hand the inside portion of the drum can plow or mound the asphalt because the tendency is for the inside portion of the drum to rotate slower than the outside portion. This is contrary to the goal of finishing a road surface that is smooth and flat.
Solutions in attempt to minimize the problem, as set forth above is to provide a drum that have first and second drum sections known as split drums. The split drum divides the width of a given drum in half allowing an outer drum section to rotate faster than an inner drum section during turning and other operations. Split drum designs are known in the art and often use a fixed friction pack to couple the two drum sections to one another. The frictional force of the friction packs must be overcome however before slip can occur between the drum sections. In operation however the split drums do not always operate in a predictable manner and slip between the sections occurs when not desired and often does not occur when slip is desired. Another attempt to address this problem is disclosed in U.S. Pat. No. 5,390,495 granted on Feb. 21, 1995 and assigned to Poclain Hydraulics. This patent teaches using independent drive motors to propel each drum section.
The present invention is directed at overcoming one or more of the problems as set forth above.
In one aspect of the present invention, a compacting drum for a work machine is provided. The compacting drum includes a first drum section and a second drum section positioned adjacent to the first drum section. A controllable coupling arrangement connects the first drum section to the second drum section.